Bypass audio resampler on XP / non-WASAPI wave out path.

media/audio/win/audio_manager_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/audio_io.h"
 
 #include <windows.h>
 #include <objbase.h>  // This has to be before initguid.h
 #include <initguid.h>
 #include <mmsystem.h>
@@ skipping 299 matching lines @@
 
   return new PCMWaveInAudioInputStream(this, params, kNumInputBuffers,
                                        xp_device_id);
 }
 
 /// static
 AudioManager* CreateAudioManager() {
   return new AudioManagerWin();
 }
 
+AudioParameters AudioManagerWin::GetPreferredLowLatencyOutputStreamParameters(
+    const AudioParameters& input_params) {
+  // If WASAPI isn't supported we'll fallback to WaveOut, which will take care
+  // of resampling and bits per sample changes.  By setting these equal to the
+  // input values, AudioOutputResampler will skip resampling and bit per sample
+  // differences (since the input parameters will match the output parameters).
+  int sample_rate = input_params.sample_rate();
+  int bits_per_sample = input_params.bits_per_sample();
+  if (IsWASAPISupported()) {
+    sample_rate = GetAudioHardwareSampleRate();
+    bits_per_sample = 16;
+  }
+
+  // TODO(dalecurtis): This should include bits per channel and channel layout
+  // eventually.
+  return AudioParameters(
+      AudioParameters::AUDIO_PCM_LOW_LATENCY, input_params.channel_layout(),
+      sample_rate, bits_per_sample, GetAudioHardwareBufferSize());
+}
+
 }  // namespace media